A topic of technical concern with surface-emitting lasers is how to emit a high-power laser beam that has a narrow angle of radiation. Japanese Patent Application Laid-Open No. 8-340156 discloses a surface-emitting laser that emits phase-synchronized laser beams from a plurality of light-emitting portions, to produce what appears to be a single laser beam, due to the interference effect of light. The apparently single laser beam was observed to have a high power level and a narrow angle of radiation.
In this surface-emitting laser, a columnar portion is formed on a cladding layer on a light-emitting side, an embedding layer is formed around the columnar portion, and an electrode on a light-emitting side has a plurality of aperture portions, where peripheral portions of the aperture portions are in contact with the columnar portion. The lasing mode of light directly under the aperture portions of the electrode is different from that directly under the peripheral portions thereof, but the plurality of laser beams emitted from the aperture portions appears to form a single laser beam.
An insulating material is used as the embedding layer in this surface-emitting laser. The refractive index of an oxide such as SiO.sub.2, a nitride such as Si.sub.3 N.sub.4, or a compound from Group II-VI such as ZnSe that is generally used as the insulating embedding layer is greatly different from the refractive index of a compound from Group III-V such as GaAs that is a compositional element of the cladding layer. Since this means that light is enclosed excessively within the central portion of the resonator, it is impossible to cut out the higher transverse modes.
The present invention was devised in order to solve the above problems of the prior art and thus provides a surface-emitting laser wherein the transverse modes are controlled and phase-synchronized laser beams are emitted from a plurality of light-emitting portions to produce what appears to be a single laser beam, and a method of fabrication thereof.